Reconcile createTopics type and behaviour

Author: milindl

lib/kafkajs/_admin.js

@@ -207,7 +207,7 @@ class Admin {
   /**
    * Create topics with the given configuration.
    * @param {{ validateOnly?: boolean, waitForLeaders?: boolean, timeout?: number, topics: import("../../types/kafkajs").ITopicConfig[] }} options
-   * @returns {Promise<void>} Resolves when the topics are created, rejects on error.
+   * @returns {Promise<boolean>} Resolves true when the topics are created, false if topic exists already, rejects on error.
    */
   async createTopics(options) {
     if (this.#state !== AdminState.CONNECTED) {
@@ -229,9 +229,13 @@ class Admin {
         .map(topicConfig => new Promise((resolve, reject) => {
           this.#internalClient.createTopic(topicConfig, options.timeout ?? 5000, (err) => {
             if (err) {
+              if (err.code === error.ErrorCodes.ERR_TOPIC_ALREADY_EXISTS) {
+                resolve(false);
+                return;
+              }
               reject(createKafkaJsErrorFromLibRdKafkaError(err));
             } else {
-              resolve();
+              resolve(true);
             }
           });
         }));